Subject: [Sip] some tcp nat tests

From: [email-masked] (Juha Heinanen)
Date: Sun, 17 Dec 2006 11:13:41 +0200

as i mentioned in an earlier message, i finally found a SIP phone that
supports SIP over TCP (Nokia N80).  during the past days i have done
some tests with it.  the setup is this:

N80 -- WLAN -- AP -- Linux with iptables NAT -- internet -- OpenSER proxy/reg

OpenSER proxy is configured to use persistent TCP connections to the
registrar if SIP UA is behind NAT.  this means that it keeps the TCP
connection open to the UA a few minutes longer than the registration
interval advertised by the phone.  it does not currently send any TCP
keepalive messages, but could be made to do so.  if SIP request comes in
bound to the UA, it reuses the existing TCP connection.

N80 registers every 3600 seconds and, in addition, it is sending a 4
byte TCP keepalive message after every 20 minutes if there has been no
other activity.  wireshark reports the TCP keepalive messages as
Continuation messages.

during the tests i have not seen any problems whatsoever.  the same TCP
connection stays up and both ways useable forever unless there is a
equipment failure.  

i still fail to see what exactly is the problem is that outbound tries
to solve which has warranted hundreds if not thousands of messages on
this mailing list.  i really would have liked to see that energy spend
on solving real problems, such as how to build a resilient, load
balancing SIP architecture.

-- juha

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---

From: Klaus Darilion <[email-masked]>
Date: Mon, 18 Dec 2006 12:55:20 +0100

> supports SIP over TCP (Nokia N80).  during the past days i have done

eyebeam and SNOM support TCP too.

> this mailing list.  i really would have liked to see that energy spend

me too. eyebeam work like a charm over TCP.

regards
klaus

-- 
Klaus Darilion
nic.at